The lithium ion secondary battery has been widely used as the power supply of notebook personal computers, video cameras, cellular phones, electric vehicles, and the like, for example. As the lithium ion secondary battery, one which is configured so that the periphery of a battery body is surrounded by a case is used. As a packaging material for case, one is known which has a configuration in which an outer layer containing a stretched polyamide film and an inner layer containing an aluminum foil layer and a thermoplastic resin are bonded and integrated in this order (Patent Document 1).
Such a packaging material for battery case has been molded into arbitrary shapes, and therefore has been demanded to have high deep drawing moldability and high projection moldability. Therefore, one having a configuration in which the surface of an outer layer film of a packaging material is coated with a fatty acid amide-based slipperiness imparting component so that slipping of the material into a die in molding is improved (Patent Document 2) and one having a configuration in which the thickness of an outer layer film is larger than the thickness of a metal foil layer have been adopted heretofore, for example.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2001-6631
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2002-216714